A colorimetric photon source is useful in calibrating the colorimetric response of a color imaging device. In addition to calibration, the response of the imaging device to a photon source of known wavelength may be measured for purposes of characterization and quality control.
It is known that reflective imaging targets may be provided for color calibration. Reflective targets for calibration generally use a reflective colorimetric substance such as paint and are illuminated with broadband (white) light sources. However, reflective targets generally have broadband reflectance, which complicates color camera calibration. Reflective targets are difficult to illuminate uniformly, as well; making the calibration more complicated. Furthermore, many pigmented paints age and consequently change their color over their lifetime, requiring frequent re-calibration of test targets.
Consequently, it is useful in the art of color imaging calibration to provide a cost effective, stable source of photons having narrow spectral power and having a uniform illumination pattern within the field of view of the imaging device to be calibrated.